The Thermosphere at Solar Minimum
Abstract
The sustained decrease in solar extreme ultraviolet radiation during the current minimum is greater than any in recent history. This gives us the opportunity to study neutral density conditions that are outside the domain of the available empirical models of the thermosphere. While there are currently no experiments measuring in-situ composition of the thermosphere, the accelerometers aboard the CHAMP and GRACE satellites provide a monitor of total atmospheric density, spanning most of solar cycle 23 through the current minimum (2001-2008). Using these data, complemented by ground-based measurements of satellite drag (1996-2008), it appears that agreement between data and empirical models is strongly dependent on satellite altitude during solar minimum, implying an error in our empirical knowledge of the atmospheric scale height. Knowledge of species-dependent behavior with respect to local-time and latitude gives us a crude method of separating the observed scale heights into the competing effects of composition and temperature changes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSA31B1413S
- Keywords:
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- 0355 ATMOSPHERIC COMPOSITION AND STRUCTURE / Thermosphere: composition and chemistry;
- 0358 ATMOSPHERIC COMPOSITION AND STRUCTURE / Thermosphere: energy deposition;
- 3369 ATMOSPHERIC PROCESSES / Thermospheric dynamics;
- 7969 SPACE WEATHER / Satellite drag